Shortcuts to reproducing part of one tree into another???

Shortcuts to reproducing part of one tree into another???

My mother and father both came from closely related ethnicity. At some places in both trees there are points where a certain ancestor or married couple are the same people. If I have one tree almost completed out, is there a way to copy and transfer a whole string of shared individuals to the other side of the tree. (Father and mother are both listed in the same tree).

Can I do this and keep the new relationships correct in the added tree information?